Jerry1996x wrote:Question. Im getting a Twin reverb, and hopefully a hard truckers 2x12. Im pretty sure twins handle up to 4 ohms. I guess that means i have to have the cab wired parallel, correct me if im wrong. Also, how will this effect the loudness of the cab?

wiring depends on the ohm rating of the speakers it will be loaded with.

Jerry1996x wrote:Question. Im getting a Twin reverb, and hopefully a hard truckers 2x12. Im pretty sure twins handle up to 4 ohms. I guess that means i have to have the cab wired parallel, correct me if im wrong. Also, how will this effect the loudness of the cab?

wiring depends on the ohm rating of the speakers it will be loaded with.

Twins work best and are factory wired with two 8ohm speakers wired in parallel for 4 ohms. The 4 ohm load will give you the best results. The lower the ohms, the more watts!

mkaufman wrote:My Twin head (Showman Reverb) has a speaker and external speaker jack. What happens to the ohms if both jacks are used?

parallel jacks: in order to have a correct 4 ohm load on the amp, you could use one jack with one 4 ohm cab, or you could have each jack going to a separate 8 ohm load (which in turn could consist of a single 8 ohm speaker, or two 16 ohm speakers wired in parallel, or two 4 ohm speakers wired in series...)... also if you are using two 8 ohm cabs and one of them has a 2 parallel jacks, you can daisy chain them one to the next out just a single amp jack and still have the correct 4 ohm load.

in other words, the speakers that you connect to the amp and how they are wired, not the jacks, are what determine the ohms that your amp "sees", as they say.

mkaufman wrote:So I can run (2) 2x12's, each with (2) 8-ohm speakers wired in parallel.

Sound easy!

Just need someone to carry my cabs!

mk

Yes! Exactly! It is very easy,and when you find someone to carry your cabs, let me know so they can carry mine too! Actually you might find out you only want/need one cab most times, but that is personal preference. I use a very well padded and cushioned hand truck with bungi cords unless I have help lol.

mkaufman wrote:So I can run (2) 2x12's, each with (2) 8-ohm speakers wired in parallel.

each cab will be rated at 4 ohm....if you connect a 4 ohm load to each of your two speaker jacks, the amp will do the math and see a 2 ohm load. probably safe for most BF/SF Twins, but the jacks are parallel, they are not "4 ohm each", the amp sees every load that gets connected

mkaufman wrote:So I can run (2) 2x12's, each with (2) 8-ohm speakers wired in parallel.

each cab will be rated at 4 ohm....if you connect a 4 ohm load to each of your two speaker jacks, the amp will do the math and see a 2 ohm load. probably safe for most BF/SF Twins, but the jacks are parallel, they are not "4 ohm each", the amp sees every load that gets connected

That is not true, mkaufman. It distinctly says on the back of my twin: 4 ohms for speaker out put and 4 ohms for extension speaker out put. It is designed to have two separate 4 ohm out puts. It also says that in the Fender Manual and I have also measured the impedence to confirm.

mkaufman wrote:So I can run (2) 2x12's, each with (2) 8-ohm speakers wired in parallel.

each cab will be rated at 4 ohm....if you connect a 4 ohm load to each of your two speaker jacks, the amp will do the math and see a 2 ohm load. probably safe for most BF/SF Twins, but the jacks are parallel, they are not "4 ohm each", the amp sees every load that gets connected

That is not true, mkaufman. It distinctly says on the back of my twin: 4 ohms for speaker out put and 4 ohms for extension speaker out put. It is designed to have two separate 4 ohm out puts. It also says that in the Fender Manual and I have also measured the impedence to confirm.

actually TS is spot on, the amp can obviously handle the 2 ohm load because that is what it will get if you throw 2 - 4 ohm cabs into it. the speaker jacks are wired in parallel internally and the output transformer will definately see this as a 2 ohm load.

peace,
waldo

Disclaimer: I get paid to make, modify or build things for those that seek what i may be able to provide.

I've looked into this more and after some research and speaking to Fender, I found out the bottom line. I was under the impression that all twins were the same in respect to the speaker and extention speaker jacks. I was wrong. The only twins that are true 4 ohms for both out puts are the 135 watt ultra linear twins with the master volume. They are also the only twins with a direct line out. Sorry for the confusion.

One of the clearest resources I've found for wiring and cab hookups are the Mesa Boogie User Manuals. Near the end they show diagrams of just about every combination you can think of. Try the Lonestar, that's the one I have.